Honestly, these kind of problems are often due to unplanned/unexpected events (disk full, wrong permissions on a folder, OS updates correcting old bugs you have

Honestly, these kind of problems are often due to unplanned/unexpected events (disk full, wrong permissions on a folder, OS updates correcting old bugs you have coded around) where having line-by-line comments would not help much if at all. I would love to work in a place where documentation was cosidered a valuable asset, but I think that your example is off mark.